There is work in anesthetized monkeys (the neural and behavioral signatures of anesthesia are similar to those of coma) demonstrating that high frequency thalamic stimulation is sufficient to restore some markers of wakefulness, even while the monkey is continuously receiving anesthetic. It’s wild.
What is the mechanism by which deep brain stimulation promotes renewal of damaged areas? The interview speaks of it as already having success with more intrusive methods. All search results for “how” seem to just describe the surgery.
I would posit that they're stimulating synaptogenesis and promoting functional connections to help counteract the loss of neurons as a result of the thalamic atrophy. In other words, stimulating the existing neurons to make more connections with the neurons available to compensate for there being less neurons.
It might rather be due to the brain simply requiring a baseline level of excitability to be present in order for it to properly function. Many unconscious states are characterized by reduced activity throughout the brain. The thalamus, being connected to practically every area of cortex, is well positioned to push the cortex into a more active state. And note that there are loops everywhere! The thalamus connects to the cortex, the cortex connects to the basal ganglia, which connects back to the thalamus. And there are many more feedback loops between these structures. So it could be that you simply need to “kickstart” the system, as this article is suggesting, and once a baseline level of excitability is reached, all of these loops do the job of keeping the system at a functioning, stable state of excitability. To what extent this leads to the repair of damaged brain areas is less clear, but we know that lack of activity causes atrophy, so pushing the system back into an excited state could in principle prevent further damage.
[0]: https://www.biorxiv.org/content/10.1101/2020.07.07.190132v1
[1]: https://www.sciencedirect.com/science/article/abs/pii/S08966...